1917] Ritter-Forsiitli : Aaridians of Southern California 447 



one between each of the two infundibula thus intercepted. Finally 

 tertiary vessels are often found on the faces of the infundibula, where 

 they divide the stigmata of the faces and separate the two short spirals 

 which, in such cases, often occur at the spaces of the infundibula. 

 Usually the stigmata at the apex of an infundibulum form a single 

 short spiral (pi. 40, fig. 16). At the posterior end of the sac, the 

 stigmata become irregular, assuming s-shaped and spiral forms. 

 Dorsal lamina a plain membrane with thiclcened edge. Endostyle 

 {end., pi. 40, fig. 15) long and slender. 



Digestive system. — Situated on left side of the body, forming a 

 long closed loop which in turn forms a regular curve on posterior 

 dorsal portion of that side (pi. 40, fig. 15). Esophagus (e), not quite 

 as long as stomach, emerges from dorsal posterior portion of branchial 

 sac. vStomach (s.) thin-walled, smooth, over twice as long as wide, 

 and of not much greater diameter than intestine. On inner surface 

 of esophagus and stomach, and extending beyond them is a voluminous 

 rosette-shaped reddish-brown liver (I., pi. 40, fig. 15). This made 

 up of two distinct portions, each consisting of numerous radiating 

 elongated caeca. Anus plain-edged, situated in peribranchial cavity 

 near the emergence of esophagus and near atrial siphon. Kidney 

 bean-shaped, and located on right side and ventral portion of the body 

 just posterior to ovary, to which it is almost equal in size. 



Reproductive sij.ttem. — Consists of- two hermaphroditic gonad.s. one 

 on each side of the body. Ovaries large, irregularly oval, somewhat 

 flattened bodies, that on left side situated just anterior to intestinal 

 loop (pi. 40, fig. 15). Short oviduct arises from anterior edge of 

 ovary and opens into peribranchial cavity where the larvae develop. 

 Specimens taken in July and in October had numerous tadpoles. 

 Testicular lobes (t., pi. 40, fig. 15) comparatively few. situated on 

 posterior border of ovary. 



Habitat and distribution. — On the exposed surfaces of rocks 

 usually, but sometimes on the under surfaces, in the littoral zone. La 

 Jolla. California. 31. verrucifera undoubtedly occurs at other places 

 than La Jolla but has not yet been collected elsewhere. 



This species belongs to the small group of molgulids in which both 

 branchial and atrial orifices are armed with well-developed processes. 

 On this basis it would fall into the genus Cetenicella as defined by 

 Lacaze-Duthiers. We agree, however, with tho.se recent aseidiologists 

 who consider the group recognized by this author as too small and 

 heterogeneous to be profitably accepted as a genus. Nor does our 

 .species come near to accommodating itself to Cetenicella as redefined 

 by Hartmeyer. There is no course open to us, therefore, but to place 

 it in the genus 3Iolgula, in which group it occupies a fairly distinct 

 place by virtue of the possession of the siphonal processes. 



The specific name has reference to the wart-like appearance of the 

 siphons even in preserved specimens. 



